- Email: [email protected]
Glass laser
The T h e r m a f i n e P r o b e is a h i g h e r powered m o r e v e r s a t i l e s o u r c e f o r g e n e r a l o p t i c a l work, it m e a s u r e s 155 × 95 x 50 mm and weights 2,500 gms. T h e r m a l Syndicate L i m i t e d , P.O. Box 6, Wallsend, Northumberland.
R O T A T I N G Q-SWITCH A ROTATING R E F L E C T O R has been designed as a l a s e r Q - s w i t c h by Hadron, New York ( F i g . 4 ) The Qs w i t c h r o t a t e s at 0-36,000 r p m , spinning e i t h e r a 1i n c h - s q u a r e roof p r i s m or a 1-inch d i a m e t e r flat, each of which has a t h r e e - q u a r t e r s of an inch m i n i m u m clear aperture. E l e c t r i c a l s i g n a l s a r e g e n e r a t e d at the r o t a t i o n a l r a t e by a photo pickup. The r o t a t i o n a l s p e e d i s c o n t r o l l e d by r e g u l a t i n g the voltage to the Q - s w i t c h m o t o r . Hadron Inc; 800 S h a m e s D r i v e , W e s t b u r y , New York 11590, U.S.A.
LIGHT SENSITIVE A R R A Y A NEW DEVICE for optical c h a r a c t e r recognition, edge s e n s i n g and width m e a s u r e m e n t is now being manuf a c t u r e d by I n t e g r a t e d P h o t o m a t r i x L i m i t e d , D o r c h e s t e r (Fig. 5). A l i n e a r a r r a y of 50 s i l i c o n p l a n a r photodiodes a r e int e g r a t e d with a 51-bit shift r e g i s t e r on a monolithic chip. The d i o d e s a r e a r r a n g e d to o p e r a t e in the light i n t e g r a t i n g mode. P r e and post s e n s o r s a r e provided b e f o r e the 1st and a f t e r the 50th d i o d e s r e s p e c t i v e l y . T h e s e m a y be used f o r the p r e - s e n s i n g of an i l l u m i n a t i o n edge or for determining general illumination level. V a r i a t i o n s in the width of a moving s t r i p of m a t e r i a l can be d e t e c t e d using two a r r a y s , even if the m a t e r i a l is not moving in a constant d i r e c t i o n . I n t e g r a t e d P h o t o m a t r i x L i m i t e d , The Grove T r a d i n g Estate, Dorchester, Dorset.
m
r
F i g . 4 Rotating r e f l e c t o r designed f o r use a s a l a s e r Q-switch.
GLASS LASER A GLASS LASER which m a k e s use of a light focusing fibre guide and can p e r f o r m s t a b l e o s c i l l a t i o n h a s been p r o d u c e d by the Nippon Company, Japan. The
RADIATION-PROOF GLASS A RADIATION PROOF WINDOW that r e m a i n s t r a n s p a r e n t and checks r a d i a t i o n has been developed by J e n n e r G l a s w e r k Schott & Gen., Mainz, f o r an a t o m i c r e a c t o r in Italy. This window p r o v i d e s p a r t i c u l a r l y good p r o t e c t i o n f r o m the g a m m a r a y s that e m a n a t e f r o m u r a n i u m e n r i c h e d fuel r o d s . The g l a s s i t s e l f has an e x t r e m e l y high lead content to p r e v e n t the e s c a p e of r a d i o - a c t i v i t y . F i v e 2 0 - c m thick panes of g l a s s a r e mounted in tandem, and the c o m p a r t m e n t s between them f i l l e d with oil to p r e v e n t reflection. Each of the five panes of g l a s s is s m a l l e r than the p r e c e d i n g one. The l a r g e end of the tunnel i s the 'hot end' in the c h a m b e r . J e n n e r G l a s w e r k Schott 5 Gen, Mainz.
62
Oplics and L a s e r Technology
F i g . 5 Light s e n s i t i v e a r r a y .
February 1971
glaSS l a s e r has advantages o v e r other solid l a s e r s : it can easily be m a d e in any d e s i r e d shape, it has excellent optical homogeneity, it is c o m p a r a t i v e l y inexpensive, and it enables the p e r f o r m a n c e of light pulse oscillation of e x t r e m e l y n a r r o w pulse-width suitable for v e r y h i g h - s p e e d digital communication by its l a s e r oscillation it had p r e v i o u s l y only been possible to p e r f o r m i n t e r m i t t e n t oscillation and it had been impossible to make the g l a s s l a s e r p e r f o r m stable and continuous wave oscillation. As shown in Fig. 6. the Selfoc l a s e r is c o n s t r u c t e d to allow the s o - c a l l e d l a s e r oscillation by housing a lightsource such a s the krypton a r c l a m p and the l a s e r element in an elliptical cavity, and exciting the Neodymium ions in the l a s e r e l e m e n t by m e a n s of the l a m p . The r e f r a c t i v e index of the l a s e r element d e c r e a s e s continuously f r o m the c e n t r a l axis towards the periphery. To p r e v e n t diffraction l o s s within the l a s e r e l e m e n t it should be of a c e r t a i n thickness. But when p e r f o r m i n g continuous wave oscillation and amplification, the l a s e r e l e m e n t is subjected to the strong excitation of the l a m p and the element is liable to b r e a k as the t e m p e r a t u r e r i s e s . The d i a m e t e r of the l a s e r e l e m e n t is t h e r e f o r e made s m a l l in o r d e r to cool it sufficiently. However, when the d i a m e t e r is small, the diffraction c a u s e s an i n c r e a s e d amount of light to e s c a p e f r o m the s u r f a c e of the l a s e r element. It was i m p o s s i b l e to produce continuous oscillation and amplification by the use of t h e conventional g l a s s l a s e r element which had a uniform r e f r a c t i v e index. In the 8elfoc l a s e r element, the light-focusing action c a u s e s the b e a m , which would n o r m a l l y expand in the hyperbolic f o r m , to return to the centre where the 100 90 80 td 7 0 ZU GO < p 50
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elliptical refteding cavity
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laser elerrient tincj water
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. . . . . .
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output mirror (~4 :'~/ output loser beam
mirror (r:O°,o)
Fig. 6 Selfoc l a s e r (oscillator) r e f r a c t i v e index is great, so preventing it f r o m colliding with the l a t e r i a l s u r f a c e s but allowing it to p a s s through the n a r r o w l a s e r element. Thus, it is possible to m i n i m i z e the l o s s of light and provide effective cooling b e c a u s e of the n a r r o w e d d i a m e t e r . This m a k e s a continuous oscillation and amplification p o s sible. The Selfoc l a s e r element has a dimension of l e s s than 1 . 5 m m in d i a m e t e r , and its length is l e s s than 40cm. In operation a Selfoc l a s e r element having a d i a m e t e r of 1 . 5 m m and a length of 10cm, produced an o s c i l l a tion of a p p r o x i m a t e l y 3.5 W continuous output at a wavelength of 1.06pm. A continuous light a m p l i f i e r of 1.06pm wavelength was also made with the s a m e element. The 8elfoc l a s e r could find a use as a s o u r c e of continuous oscillation of u l t r a - h i g h - s p e e d pulse c o m m u n i cation at a p i c o - s e c o n d unit which had not been cons l d e r e d possible in the past.
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WAVELENGTH
O.C.L.I. produce thin film coatings to enhance the energy transmitted or reflected by optics in the Ultra-violet, visible, and Infra-red regions of the electro magnetic spectrum. O.C.L.I.'s expertise enables us to position the edges and centre wavelengths of square bandpass, short wave and long wave pass filters accurately throughout these regions. Thin film coated optics for visible and infra-red systems are manufactured from such materials as glass, quartz, silicon, germanium, etc.,
11
12
13
14
15
(MICRONS)
and will withstand military environmental c o n d i t i o n s , a n d a r e d u r a b l e , s t a b l e and i m pervious to moisture. S o m e p r o d u c t s a r e listed b e l o w : Single/multilayer anti-reflection coatings. H e a t / l i g h t s e p a r a t i o n filters. C o l o u r s e p a r a t i o n filters. B e a m s p l i t t e r s / c o m bining m i r r o r s . High reflectors. Laser coatings and optics.
O.C.L.I. Optical Coatings Limited HILLEND INDUSTRIAL ESTATE DUNFERMLINE, FIFE Phone; Inverkeithing 3631
Optics and Laser Technology
February 2971
63
R O T A T I N G Q-SWITCH A ROTATING R E F L E C T O R has been designed as a l a s e r Q - s w i t c h by Hadron, New York ( F i g . 4 ) The Qs w i t c h r o t a t e s at 0-36,000 r p m , spinning e i t h e r a 1i n c h - s q u a r e roof p r i s m or a 1-inch d i a m e t e r flat, each of which has a t h r e e - q u a r t e r s of an inch m i n i m u m clear aperture. E l e c t r i c a l s i g n a l s a r e g e n e r a t e d at the r o t a t i o n a l r a t e by a photo pickup. The r o t a t i o n a l s p e e d i s c o n t r o l l e d by r e g u l a t i n g the voltage to the Q - s w i t c h m o t o r . Hadron Inc; 800 S h a m e s D r i v e , W e s t b u r y , New York 11590, U.S.A.
LIGHT SENSITIVE A R R A Y A NEW DEVICE for optical c h a r a c t e r recognition, edge s e n s i n g and width m e a s u r e m e n t is now being manuf a c t u r e d by I n t e g r a t e d P h o t o m a t r i x L i m i t e d , D o r c h e s t e r (Fig. 5). A l i n e a r a r r a y of 50 s i l i c o n p l a n a r photodiodes a r e int e g r a t e d with a 51-bit shift r e g i s t e r on a monolithic chip. The d i o d e s a r e a r r a n g e d to o p e r a t e in the light i n t e g r a t i n g mode. P r e and post s e n s o r s a r e provided b e f o r e the 1st and a f t e r the 50th d i o d e s r e s p e c t i v e l y . T h e s e m a y be used f o r the p r e - s e n s i n g of an i l l u m i n a t i o n edge or for determining general illumination level. V a r i a t i o n s in the width of a moving s t r i p of m a t e r i a l can be d e t e c t e d using two a r r a y s , even if the m a t e r i a l is not moving in a constant d i r e c t i o n . I n t e g r a t e d P h o t o m a t r i x L i m i t e d , The Grove T r a d i n g Estate, Dorchester, Dorset.
m
r
F i g . 4 Rotating r e f l e c t o r designed f o r use a s a l a s e r Q-switch.
GLASS LASER A GLASS LASER which m a k e s use of a light focusing fibre guide and can p e r f o r m s t a b l e o s c i l l a t i o n h a s been p r o d u c e d by the Nippon Company, Japan. The
RADIATION-PROOF GLASS A RADIATION PROOF WINDOW that r e m a i n s t r a n s p a r e n t and checks r a d i a t i o n has been developed by J e n n e r G l a s w e r k Schott & Gen., Mainz, f o r an a t o m i c r e a c t o r in Italy. This window p r o v i d e s p a r t i c u l a r l y good p r o t e c t i o n f r o m the g a m m a r a y s that e m a n a t e f r o m u r a n i u m e n r i c h e d fuel r o d s . The g l a s s i t s e l f has an e x t r e m e l y high lead content to p r e v e n t the e s c a p e of r a d i o - a c t i v i t y . F i v e 2 0 - c m thick panes of g l a s s a r e mounted in tandem, and the c o m p a r t m e n t s between them f i l l e d with oil to p r e v e n t reflection. Each of the five panes of g l a s s is s m a l l e r than the p r e c e d i n g one. The l a r g e end of the tunnel i s the 'hot end' in the c h a m b e r . J e n n e r G l a s w e r k Schott 5 Gen, Mainz.
62
Oplics and L a s e r Technology
F i g . 5 Light s e n s i t i v e a r r a y .
February 1971
glaSS l a s e r has advantages o v e r other solid l a s e r s : it can easily be m a d e in any d e s i r e d shape, it has excellent optical homogeneity, it is c o m p a r a t i v e l y inexpensive, and it enables the p e r f o r m a n c e of light pulse oscillation of e x t r e m e l y n a r r o w pulse-width suitable for v e r y h i g h - s p e e d digital communication by its l a s e r oscillation it had p r e v i o u s l y only been possible to p e r f o r m i n t e r m i t t e n t oscillation and it had been impossible to make the g l a s s l a s e r p e r f o r m stable and continuous wave oscillation. As shown in Fig. 6. the Selfoc l a s e r is c o n s t r u c t e d to allow the s o - c a l l e d l a s e r oscillation by housing a lightsource such a s the krypton a r c l a m p and the l a s e r element in an elliptical cavity, and exciting the Neodymium ions in the l a s e r e l e m e n t by m e a n s of the l a m p . The r e f r a c t i v e index of the l a s e r element d e c r e a s e s continuously f r o m the c e n t r a l axis towards the periphery. To p r e v e n t diffraction l o s s within the l a s e r e l e m e n t it should be of a c e r t a i n thickness. But when p e r f o r m i n g continuous wave oscillation and amplification, the l a s e r e l e m e n t is subjected to the strong excitation of the l a m p and the element is liable to b r e a k as the t e m p e r a t u r e r i s e s . The d i a m e t e r of the l a s e r e l e m e n t is t h e r e f o r e made s m a l l in o r d e r to cool it sufficiently. However, when the d i a m e t e r is small, the diffraction c a u s e s an i n c r e a s e d amount of light to e s c a p e f r o m the s u r f a c e of the l a s e r element. It was i m p o s s i b l e to produce continuous oscillation and amplification by the use of t h e conventional g l a s s l a s e r element which had a uniform r e f r a c t i v e index. In the 8elfoc l a s e r element, the light-focusing action c a u s e s the b e a m , which would n o r m a l l y expand in the hyperbolic f o r m , to return to the centre where the 100 90 80 td 7 0 ZU GO < p 50
I I
i- 40 30
t
o•.
I/I z < ~c
i i
20
t
10
t 5
G
elliptical refteding cavity
±/.Kr- arc-lamp
I
Ii ; r~_
El
~ exciting
, I
iL~f ~ ~
I ..i ,L
laser elerrient tincj water
l
~
light
. . . . . .
"J~'~~
output mirror (~4 :'~/ output loser beam
mirror (r:O°,o)
Fig. 6 Selfoc l a s e r (oscillator) r e f r a c t i v e index is great, so preventing it f r o m colliding with the l a t e r i a l s u r f a c e s but allowing it to p a s s through the n a r r o w l a s e r element. Thus, it is possible to m i n i m i z e the l o s s of light and provide effective cooling b e c a u s e of the n a r r o w e d d i a m e t e r . This m a k e s a continuous oscillation and amplification p o s sible. The Selfoc l a s e r element has a dimension of l e s s than 1 . 5 m m in d i a m e t e r , and its length is l e s s than 40cm. In operation a Selfoc l a s e r element having a d i a m e t e r of 1 . 5 m m and a length of 10cm, produced an o s c i l l a tion of a p p r o x i m a t e l y 3.5 W continuous output at a wavelength of 1.06pm. A continuous light a m p l i f i e r of 1.06pm wavelength was also made with the s a m e element. The 8elfoc l a s e r could find a use as a s o u r c e of continuous oscillation of u l t r a - h i g h - s p e e d pulse c o m m u n i cation at a p i c o - s e c o n d unit which had not been cons l d e r e d possible in the past.
I
!-
! ! i
I i, 7
i i
8
9
10
WAVELENGTH
O.C.L.I. produce thin film coatings to enhance the energy transmitted or reflected by optics in the Ultra-violet, visible, and Infra-red regions of the electro magnetic spectrum. O.C.L.I.'s expertise enables us to position the edges and centre wavelengths of square bandpass, short wave and long wave pass filters accurately throughout these regions. Thin film coated optics for visible and infra-red systems are manufactured from such materials as glass, quartz, silicon, germanium, etc.,
11
12
13
14
15
(MICRONS)
and will withstand military environmental c o n d i t i o n s , a n d a r e d u r a b l e , s t a b l e and i m pervious to moisture. S o m e p r o d u c t s a r e listed b e l o w : Single/multilayer anti-reflection coatings. H e a t / l i g h t s e p a r a t i o n filters. C o l o u r s e p a r a t i o n filters. B e a m s p l i t t e r s / c o m bining m i r r o r s . High reflectors. Laser coatings and optics.
O.C.L.I. Optical Coatings Limited HILLEND INDUSTRIAL ESTATE DUNFERMLINE, FIFE Phone; Inverkeithing 3631
Optics and Laser Technology
February 2971
63